The present invention relates to a card connector mounted on electronic devices, such as cellular phones, telephones, PDAs (personal digital assistants), portable audio devices and cameras, and more specifically to a structure that prevents contact terminals of the card connector from being deformed by a wrong insertion of a card.
In electronic devices such as cellular phones, telephones, PDAs and digital cameras, a variety of functions are added by inserting an IC card with a built-in CPU or memory IC, such as a SIM (subscriber identity module) card, an MMC (multimedia card), and an SD (secure digital or super density) card.
In a connector for removably accommodating such an IC card, a plurality of contact terminals made from a metal leaf spring are provided in a connector housing to make contact with a plurality of contact pads formed on the front or back surface of the inserted IC card to electrically connect the IC card to the electronic device mounting that connector. The contact pads of the IC card include a power supply pad connected to a power supply line and a plurality of signal pads for transferring various signals. These contact pads are connected via the contact terminals of the card connector to a power supply circuit and various signal processing circuits in the electronic device.
The SD card, one kind of the IC card, is shaped as shown in FIGS. 8A to 8C and FIG. 9. FIG. 8 shows a top view of the card and FIG. 9 shows a bottom view of the card.
In these figures, the SD card 20 has an upper body portion 21 with a thickness of a. At the front right corner the card has a virtually triangular cut-off corner portion 22 for preventing its erroneous insertion. On the back surface side of the upper body portion 21 is formed a lower body portion 23 having a thickness slightly narrower than that of the upper body portion 21 and a predetermined thickness b. That is, the card 20 has stepped portions 24 formed along its both side edges.
On the front part of the lower body portion 23 a plurality of recessed portions (grooves) 26 are formed, separated from each other by a plurality of partition walls 25. On the bottom surface of these recessed portions 26 are arranged contact pads 27 connected to an IC circuit inside the card. The depth of each recessed portion 26 is almost equal to the height of the lower body portion 23 and therefore the surface of each contact pad 27 is spaced from the front surface of the upper body portion 21 by a distance equal to the thickness a of the upper body portion 21. On a side surface of the card 20 is arranged a slidable write protect button 28 which is slid to one position to protect the card 20 against being written with data.
As an example of connector for accommodating a double-height structure card, such as the SD card described above, the applicant of this invention filed Japanese Patent Application No. 11-316110 entitled xe2x80x9cCard Connector Structurexe2x80x9d on Nov. 5, 1999.
According to the invention of this application, in order to provide a connector that can be used commonly for a double-height thick card 20 such as the SD card above and for a single-height thin card (e.g., MMC card) having almost the same thickness a as the upper body portion 21 of the SD card 20, both side wall portions of a connector housing are formed with a pair of guide grooves that support and guide both side edges of the upper body portion 21 of the double-height thick card 20 and both side edges of the single-height thin card as they are inserted or withdrawn. These guide grooves support those portions of the two cards which have the same thicknesses a. In this connector, when each of these cards is supported in the connector, the distance from the contact pads 27 of one card to the contact terminals of the connector is equal to the distance from the contact pads 27 of the other card to the contact terminals, so that the both cards engage the contact terminals with the same contact pressures.
FIGS. 10A and 10B show the double-height thick card 20 normally inserted into connector 100 of this invention. A base plate of a connector housing 101 has a plurality of contact terminals 102 arranged parallelly thereon. The connector housing 101 has an abutment wall 103 against which the inserted IC card 20 is pushed. At one corner of the abutment wall 103 there is formed a protruding corner wall 104 with which the cut-off corner portion 22 of the IC card 20 engages. In both side wall portions, the above-described guide grooves 105 are formed. These paired guide grooves 105 support both edges of the upper body portion 21 of the card 20.
In FIG. 10A and FIG. 10B the card 20 is shown to be normally inserted, so contact portions 102a of the contact terminals 102 of the connector 100 engage with the contact pads 27 of the SD card 20 with an appropriate pressure.
In the connector above, when the card 20 is wrongly inserted back to front as shown in FIG. 11A and FIG. 11B, the card 20 can be inserted into the connector 100 until its rear end wall 29 abuts against the corner wall 104.
When the card is inserted back to front to such a position, however, the contact portions 102a of the contact terminals 102 are in an overloaded state where they are pressed excessively by the bottom surface of the card 20. In this state, the contact terminals 102 are deformed excessively beyond the elastic limit and undergo plastic deformations.
The present invention has been accomplished to overcome this problem. It is therefore an object of this invention to solve the problem by providing a card connector which, if the card is wrongly inserted back to front, can reliably prevent excess deformations of the contact terminals.
According to one aspect, the present invention provides a card connector for holding a card in a connector housing in such a way that contact pads of the card engage with contact terminals arranged in the connector housing, wherein the card has a plurality of recessed portions formed parallelly in a front part thereof with the contact pads arranged in the recessed portions, the card connector comprising: a pair of guide grooves formed in the connector housing to support and guide both side edges of the card; and a raised portion formed in the connector housing to fit into one of the plurality of recessed portions of the card when the card is inserted into the connector.
With this invention, when the card is inserted normally, the raised portion fits into one of the recessed portions in the card for the contact pads. At this time, the contact pads of the card are brought into contact with the contact terminals of the connector without interference from the raised portion.
When the card is wrongly inserted back to front, on the other hand, the raised portion works as a stopper and stops the card being inserted before the contact terminals are displaced by the card in excess of their elastic limit.